Question 802617
Let {{{ n }}} = number of years from now
when I am twice as old as my brother
{{{ 12 + n = 2*( 5 + n ) }}}
{{{ 12 + n = 10 + 2n }}}
{{{ n = 2 }}}
In 2 years  I will be twice as old as my brother
check:
{{{ 12 + 2 = 14 }}}
{{{ 5 + 2 = 7 }}}
{{{ 14 = 2*7 }}}
OK